Seasonal variation of solar tides in the troposphere and lower stratosphere over Gadanki: Comparisons with the global scale wave model

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Abstract

[1] Diurnal cycle hourly horizontal wind measurements by VHF radar in the altitude range of 3–20 km made at a low-latitude station, Gadanki (13.5°N, 79.2°E), are used to investigate seasonal variation of tidal parameters. The observations are compared with the recent updated version of the global scale wave model (GSWM-2000). Measured amplitudes are found to be much larger than model values, the discrepancy being larger in convective seasons, particularly for zonal winds. Observations suggest superposition of nonmigrating modes on normal migrating tides. The comparison between the observed and model is good in phase behavior, especially for meridional winds. The terdiurnal component is found to have significant amplitude. Energy densities of tidal components become maximum in the upper troposphere and get reduced in the lower stratosphere. However, the seasonal variations deserve further investigation with longer data sets and with a stress on interannual variability.

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